Process for the preparation and preservation of viscose solutions of cellulose for the production of films, threads, and filaments



@NHTE@ STATES PATENT @FFHQE.

WALDEMAR OSCAR MITSCHERLING, OF WILMINGTON, DELAWARE, ASSIGNOR T0 ATLAS POWDER COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF- DELAWARE.

]PROCESS FOR THE PREPARATION AND PRESERVATION OE VISGOSE SOLUTIONS OF CELL'UJLOSE FOR THE PRODUCTION OF FILMS, THREADS, AND FILANLENTS.

K0 Drawing.

To all whom it may concem:

Be it known that I, WALDEMAR OSCAR MITSCHERLING citizen of the United States. residing at New Castle and State of Delaware, have invented certain new and useful Improvements in Processes for the Preparation and Preservation of Viscose Solutions of Cellulose for the Production of Films, Threads, and Filaments, of which the following is a specification.

This invention relates to a process for the preparation and preservation" of viscose solutions of cellulose for the production of films, threads and filaments. Heretofore it has been common to treat cellulose with a.

solution of caustic soda and to then treat the resultant press cake, afterageing of the latter, with carbon bisulphide in an amount equal to 40-60% of the weight of the cellulose used. This resulted i giving a strawcolored viscous mass, which upon subjection to a suitable caustic alkali solution of about 10% alkalinityyielded a 56% spinning solution of cellulose. Solutions prepared in this manner are unstable and gradually decompose so that the mass sets up to a solid jelly in about a week. In consequence the before setting solution must be spun awa up takes place, i. e. usually within about four days from the time the carbon bisulphide (CS is used. v

It is a well known fact that the threads or films obtained when the solution is fresh p are better than when an older solution is used so that the quality of the product varies continuously due to the progressive deoom osition of the viscose solution. It is manifest, therefore, that anything which will arrest this decomposition and-increase the length of time during which such solutions may be advantageously used is of utility and value. I have discovered that,

' since in the decomposition of viscose solu- Speciflcation of Letters Patent.

Wilmington, in the county ofmama May a, 1922.

Application filed February 9, 1922. Serial No. 585,370.

tions thiosulphates-are formed, the addition .get a more uniform product and obviates the necessity of spinning away a solution in four or five days. By using an amount of sodiumthiosulphate equal to one percent of the cellulose used, the keeping qualities of the solutions have been prolonged, at least, to thirty days. The thiosulphate acts as a preserva-- tive and prevents or materially retards the decomposition of the cellulose into sugars, or as it is sometimes expresed, into alcohols of the multiple type. The thiosulphate does away with or obviates the addition of sugars, glycerin. and other alcohols of the multiple type which have been used hitherto to prevent or retard the decomposition of the cellulose molecule.

While the proportion of thiosulphate above mentioned has been found effective for the purposes desired it is to be understood that it is not the intention to limit the amount to be used to this particular figure.

Having described by invention, what I claim is:

1. The herein'described process of preserving viscose cellulose solutions which consists'of adding sodium-thiosulphate to such solutions.

2. The herein described process of preserving viscose cellulose solutions from decomosition which consists of adding sodiumthiosul hate to such solutions in the proportion 0 one percent of sodium-thiosulphate to the amount of cellulose lution. I i

In testimony whereof I aflix'my signature in the presence of two witnesses. WALDEMAR OSCAR MITSCHERLING.

Witnesses:

Fnnnniuc BONNET, Jr., THoM As J.,LAFFEY.

used in' such so- 

